What does a Cocoi Heron look like?
Adults have a distinctive black marking on their head, cheeks and crown that extends all the way underneath the eye. The upper parts, wings and under-wing are mainly grey, but the flight feathers are a darker grey when compared to the wing coverts. The underparts are predominately white – including the neck. The foreneck does however have some black streaking in the centre which runs from the breast up to the throat. The flanks and belly are black. The bill, which is long and sharp, is yellow with a grey upper case. The feet and legs are black, and the eyes are mainly yellow and have greenish-blue surrounding skin (lores). Both the sexes are similar in their plumage.
During the breeding season, the bill becomes a brighter yellow with a red base. The back, lower neck feathers and crest also become longer. Legs also become a reddish colour and the skin on the face becomes brighter.
Juvenile Cocoi herons are similar in appearance to adult birds but usually have greyer necks, thighs and undertails. The black cap is also duller. Immature birds can also show a brownish wash on their wings. Young birds can sometimes be confused with the similar great blue heron, but they will always display the black cap.
What does a Cocoi Heron sound like?
As with many other species of large heron, the Cocoi heron is mainly vocal when roosting or at colonies. The most common sound is a ‘rraahbm rraabb’ guttural call. In flight, these birds will often produce a ‘gawk uk, guk uk, guk uck uck’ sound.
What does a Cocoi Heron eat?
The diet of a Cocoi Heron will vary depending on the range, but generally, they’ll mainly consume large fish (up to 20cm long), aquatic insects and amphibians, such as frogs. Less frequently, they are known to eat dead or dying animals. Most of the prey is taken whilst standing and usually on their own, but they do occasionally feed in large groups of their own, or join other waterbirds if food is abundant.
For more information on what herons eat, check out this article.
Distribution and Range
Cocoi Herons can be found in most parts of South America, excluding the high Andes. They range all the way from Panama, to Chile and Argentina.
Although most birds are believed to be sedentary, it’s thought that birds in the far south may migrate to more northern parts of South America during the winter. These birds are also often accidental visitors to the Falkland Islands from time to time, mainly between February and May and also September.
Non-breeding birds can be found as Trinidad between the months of January and June.
Signs and Spotting tips
As with other herons, the Cocoi heron is a shy bird and can mainly be spotted on its own. It’s considered one of the easier herons to see and will often be seen in one of its preferred habitats along rivers and marshes foraging for fish.
Whilst in flight, these birds can be quite easy to spot and identify, as they are quite slow in the air. The large, powerful wings make Cocoi herons strong fliers and also able to take off from the water.
Breeding
The breeding season varies depending on the location of the birds, in July in Surinam and between August and November in both Brazil and Argentina.
Nests are generally built in either trees or bushes (including cacti) but can also be made in reedbeds. The nests are made out of a combination of reeds and twigs which is then lined with a layer of grass. It takes an average of a week for the nest of a Cocoi heron to be complete.
One clutch of 3-4 light blue eggs (with white speckling) will be laid by the female, which will then be incubated by both parents for up to 26 days. Once young birds hatch, they’ll stay in and around the nests for up to 12 weeks, but will begin to wander about at around 6 weeks old.
How long do Cocoi Herons live for?
The average lifespan of a Cocoi Heron is thought to be around 10 and a half years, although they have been recorded at ages of up to 25 years.